Composition comprising long chain dibasic acids and electrolytic solution using thereof

Abstract

A mixture of long-chain dibasic acids comprising one or more long-chain dibasic acid having an alkyl group at its side chain and one or more long chain dibasic acid having a carbon chain of 8 or more carbon atoms between both its carboxyl groups and having an alkyl group and one or more alkoxycarbonyl group at its side chain is provided. This mixture can be used as the electrolyte of an electrolytic solution for electrolytic capacitors. This electrolytic solution can be produced very simply, hardly raises any precipitation at low temperatures and is tolerant to high voltage.

What is claimed is:  
     
       1. A composition for an electrolytic solution comprising a mixture of long chain dibasic acids and/or salts thereof, 
       wherein the mixture of long chain dibasic acids comprises one or more long chain dibasic acids having an alkyl group at its side chain and one or more long chain dibasic acids having a carbon chain of 8 or more carbon atoms between both its carboxyl groups and having at its side chain an alkyl group and one or more alkoxycarbonyl groups.  
     
     
       2. The composition for an electrolytic solution according to claim  1 , wherein the salt is an ammonium salt. 
     
     
       3. The composition for an electrolytic solution according to claim  2 , wherein the long chain dibasic acids and/or ammonium salts thereof are dissolved in ethylene glycol. 
     
     
       4. An electrolytic solution for electrolytic capacitors which comprises a mixture of long chain dibasic acids and/or salts thereof, 
       wherein the mixture of long chain dibasic acids comprises one or more long chain dibasic acids having an alkyl group at its side chain and one or more long chain dibasic acids having a carbon chain of 8 or more carbon atoms between both its carboxyl groups and having at its side chain an alkyl group and one or more alkoxycarbonyl groups.  
     
     
       5. The electrolytic solution for electrolytic capacitors according to claim  4 , wherein the salt is an ammonium salt. 
     
     
       6. The electrolytic solution for electrolytic capacitors according to claim  5 , wherein the dibasic acids and/or ammonium salts thereof are dissolved in ethylene glycol. 
     
     
       7. A method for producing an electrolytic solution for electrolytic capacitors, wherein the solution comprises one or more long chan dibasic acid and/or ammonium salt thereof having an alkyl group at its side chain and one or more long chain dibasic acid having a carbon chain of 8 or more carbon atoms between both its carboxyl groups and having at its side chain an alkyl group and one or more alkoxycarbonyl group, and wherein the method comprises the following steps of: 
       (1) synthesizing a mixture of long chain dibasic acid-esters by reacting an alkyl-substituted cycloalkanone and an alkyl methacrylate,  
       wherein the alkyl-substituted cycloalkanone has the following general formula (I):                    
       wherein n is an integer of 2 to 4, and R is H or a lower alkyl group having carbon number 1 to 4, wherein the alkyl group can be straight or branched;  
       (2) producing a mixture of long chain dibasic acids by hydrolyzing the thus-obtained long chain dibasic acid-esters;  
       (3) treating the thus-obtained mixture of long chain dibasic acids with ammonia; and  
       (4) dissolving the thus-obtained mixture of long chain dibasic acids and/or ammonium salt thereof in a solvent.  
     
     
       8. A composition for an electrolytic solution comprising a mixture of long chain dibasic acids and/or salts thereof, 
       wherein the mixture of long chain dibasic acids is obtained by the following method comprising the steps of:  
       (1) reacting hydrogen peroxide and cyclohexanone in methanol in the presence of an acid catalyst;  
       (2) reacting methyl methacrylate with the product of step (1) in the presence of a metal salt; and  
       (3) hydrolyzing the reaction product of step (2), and  
       wherein the mixture contains 2-methyinonanedioic acid, 2,4-dimethyl-4-methoxycarbonylundecanedioic acid, 2,4,6-trimethyl-4,6-dimethoxycarbonyltridecanedioic acid, and 8, 9-dimethyl-8,9-dimethoxycarbonylhexadecanedioic acid.  
     
     
       9. An electrolytic solution for electrolytic capacitors which comprises a mixture of long chain dibasic acids and/or salts thereof, 
       wherein the mixture of long chain dibasic acids is obtained by the following method comprising the steps of:  
       (1) reacting hydrogen peroxide and cyclohexanone in methanol in the presence of an acid catalyst;  
       (2) reacting methyl methacrylate with the product of step (1) in the presence of a metal salt; and  
       (3) hydrolyzing the reaction product of step (2), and  
       wherein the mixture contains 2-methylnonanedioic acid, 2,4-dimethyl-4-methoxycarbonylundecanedioic acid, 2,4, 6-trimethyl-4,6-dimethoxycarbonyltridecanedioic acid, and 8,9-dimethyl-8,9-dimethoxycarbonylhexadecanedioic acid.  
     
     
       10. The electrolytic solution for electrolytic capacitors according to claim  9 , wherein the salt is an ammonium salt.